This image from Syrian state television shows the aftermath of a truck bomb attack Sunday in Hama, Syria. Syria’s state media and activists say the suicide truck bomb attack on a government checkpoint on the edge of the central city left more than two dozen people dead.

BEIRUT — An international conference aimed at ending Syria’s civil war is planned for Nov. 23, the head of the Arab League said Sunday, although the U.N. envoy to Syria said the date has yet to be finalized and that peace talks will not be held “without a credible opposition.”

For months, the United States and Russia have been working to bring the Damascus government and Syria’s divided opposition to Geneva to discuss a political solution to the civil war, but the meeting has been repeatedly postponed. Even now, it remains unclear whether either side is really willing to negotiate while the conflict, now in its third year, remains deadlocked.

The main Western-backed opposition umbrella group, the Syrian National Coalition, is scheduled to meet Nov. 1 to decide whether or not to attend the proposed Geneva conference. One of the most prominent factions within the Coalition, the Syrian National Council, has said it has no faith in such talks and won’t attend.

Many rebel fighters on the ground flatly refuse to negotiate with the regime. The government, meanwhile, has refused to talk with the armed opposition.

Speaking at Arab League headquarters in Cairo, League chief Nabil Elaraby said the Geneva conference would be held on Nov. 23. He added that “many difficulties” face the proposed peace talks, but stressed that “it’s time that the killings and the bloodshed stopped.”

The Arab League-U.N. envoy to Syria, Lakhdar Brahimi, struck a more cautious tone and emphasized that the timing of the conference is not yet set. He said he must first visit Qatar and Turkey — two key supporters of the rebellion — and then meet with U.S. and Russian officials in Geneva before a final date will be announced.

On the key issue of who will take part in the talks, Brahimi said the negotiations “will not be held without a credible opposition, representing an important part of opposition within Syrian people.”

But at the same time, he said: “It is not important that all — either armed or non-armed opposition — join in the meeting as those who won’t participate will be included in Geneva 2 subsequent phase.”

Now in its third year, Syria’s conflict has killed more than 100,000 people, devastated the nation’s economy and forced some 2 million Syrians to seek refuge abroad.

The Geneva talks have been put off repeatedly for months, in part because of fundamental disagreements over Assad’s fate.

In the past, the Coalition has said that it will only negotiate if it is agreed from the start that Assad will leave power before the transition period can begin.

The regime has rejected demands for Assad to leave, saying the president will stay at least until the end of his term in mid-2014, and he will decide then whether to seek re-election. The regime has refused to negotiate with the armed opposition.

Islam Alloush, a spokesman for one rebel group, Liwaa al-Islam, said that holding a conference that involved the Syrian regime could make the conflict worse, by emboldening government forces to act more harshly on the ground.

“This is very, very sensitive. We have to be extremely careful,” Alloush said. “It could produce more negative results.”

While the international community tried to convene peace talks, the fighting on the ground has shown no sign of abating.

On Sunday, rebels drove a truck laden with more than a ton of explosives into a government checkpoint on the outskirts of the central city of Hama, the state news agency SANA said. A nearby truck carrying gasoline cylinders was caught up in the explosion, prompting a series of other blasts. Footage aired on Syrian television showed rubble, fires, and bodies on the ground.

The British-based Syrian Observatory for Human Rights said the al-Qaida-linked Jabhat al-Nusra carried out the attack. Both SANA and the Observatory said at least 30 people were killed.

It was the second deadly assault on a government post in two days. On Saturday, rebels led by fighters from Jabhat al-Nusra set off a car bomb while assaulting a checkpoint near Damascus, killing 16 soldiers.

The high-profile role played by Jabhat al-Nusra and other al-Qaida-linked militants, who have become some of the most powerful rebel factions and do not acknowledge the Western-backed Coalition, underscores the challenges of brokering a political settlement to the conflict.

Also Sunday, activists said they were still searching for news of imprisoned Syrian women who Lebanese officials say were to be freed as part of an ambitious three-way hostage release deal implemented.

But Syrian activists contacted throughout the country said they had not been able to confirm if any women were freed.

Syrian officials would not comment, and official state media did not mention the issue.

The hostage deal released nine Lebanese Shiites abducted in Syria and two Turkish pilots held hostage in Lebanon. They returned home Saturday night.

The deal, mediated by Qatar and Palestinian officials, also was meant to include freeing dozens of women held in Syrian government jails to satisfy the rebels who abducted the nine Lebanese a year and a half ago. The Turkish pilots were kidnapped in August by gunmen in Lebanon to pressure Turkey to help release the Lebanese pilgrims. Turkey is believed to have some clout with some brigades of Syrian rebels.